The present invention relates to an arrangement in a so-called one-use syringe or self-destructing syringe, especially a self-destructing hypodermic syringe of the type which generally comprises a syringe housing, a plunger with plunger rod, a plunger head with associated seal and an injection needle.
To be more specific, the invention relates to an arrangement in a needle holder for a syringe of this kind wherein the needle holder is equipped with means which render the syringe self-destructing.
The syringe is of the type that is destroyed on use and which then can be easily disposed of as the injection needle is withdrawn into the syringe housing on destruction of the syringe.
Disposable or self-destructing syringes are enjoying an ever-growing market, not least because it has become very much more common for sick persons to inject themselves. This is true in the case of, e.g., diabetic patients.
However, there is also a large an undesirable market for hypodermic syringes, namely addicts who take drugs by injection, and this user category in particular has been highly exposed to various illnesses the transmission of which is due to uncritical use of syringes.
The need for inexpensive and simple, but nevertheless dependable, self-destructing disposable syringes is therefore still very great, as an element in the battle against the spread of disease by transmission via the blood stream due to the aforementioned uncritical use of syringes.
As examples of the most common, infectious diseases today which are thus transmitted today, mention can be made of hepatitis B and AIDS.
There are various auto-destruct hypodermic syringes on the market and several syringes are known, for example, that are of the type which have a frangible member that is broken after the syringe has been used for the first time.
Many of the proposed solutions have either been too costly or too unsafe as it has been possible to manipulate the syringe so as to render it re-usable.
As regards syringes of this kind, reference will be made to NO 163 263-B and NO 301 523-C.
Another type of syringe is described in Norwegian Application 970576. This application describes syringes of the type wherein the needle holder and needle are secured to the syringe against a force which is released when the injection has been given, and wherein the needle holder and needle are withdrawn into the syringe which may then be easily disposed of.
The present invention is a further development of the technology described in P970576.
The syringes described in P970576 are simple, safe to use and safe to dispose of. However, they necessitate the availability of a large number of complete syringes.
However, the market has expressed a need to be able to equip a standard syringe housing with a mountable injection needle which is chosen according to need, yet without having to forgo the self-destructing properties of the earlier syringes.
The object of the present invention is to provide a syringe of this kind.
Accordingly, the present invention relates to an arrangement in a needle holder unit capable of being mounted on a syringe housing for self-destructing hypodermic and similar syringes, and the invention is characterised in that the needle holder is equipped with medically acceptable chemical agents for retracting the needle holder into the syringe housing.
The preferred propellant-generating chemical is crystalline formic acid and calcium carbonate and/or another similar compound which on the penetration of moisture gives off CO2 as a propellant gas.